Radiomicrosphere Dosimetry: Principles and Current State of the Art

Radiomicrosphere Therapy (RMT) refers to a liver-directed therapeutic modality based on the intrahepatic arterial administration of radiolabeled microspheres. There is a need for standardization of the terminology of RMT. A descriptive identifier should first name the radioisotope, then the chemical formulation of the microsphere, and lastly add the term RMT that indicates the therapeutic modality. At present, clinically available options include |Y-90| |Resin| |RMT|, |Y-90| |Glass| |RMT| and |Ho-166| |PLLA| |RMT|. The latter is available in Europe and is being considered for clearance by the FDA in the United States. Preclinical studies with |Re-188| |PLLA| |RMT| are underway. Dosimetric considerations are strongly tied to both the type of the radioisotope and the chemical composition of the microsphere type. This review will focus on Y-90 resin and glass RMT, the history, dosimetry, clinical use, and controversies.